Side airbag packaged in side of seat

An apparatus for helping to protect occupants of a vehicle seat in response to a vehicle collision, the vehicle seat including a base including a bottom cushion, a backrest including a back cushion, and a side rest that extends upward above the bottom cushion and forward of the back cushion, forming an upper surface configured to support an occupant's arm in a resting position, the apparatus comprising:

• a side airbag having a stored, pre-deployment condition in the side rest, the side airbag being inflatable to a deployed condition in which the side airbag cushions the occupant against impacts with the side rest, the side airbag when in the deployed condition extending upward above the bottom cushion and forward of the back cushion, the side airbag comprising a lower portion configured to deploy between the side rest and the occupant and an upper portion configured to deploy above the side rest, adjacent the occupant;
• and
• at least one internal tether having a first end connected to an inboard panel in the lower portion of the side airbag and a second end connected to an outboard panel in the upper portion of the side airbag, the at least one tether extending between the inboard and outboard panels diagonally, wherein the at least one tether is configured so that the side rest acts as a reaction surface for resisting outboard bending movement of portions of the side airbag above the side rest.